As defined by the 1997 Mine Ban Treaty (or, to give it its full name: The Convention on the Prohibition of the Use, Stockpiling, Production and Transfer of Anti-Personnel Mines and on their Destruction), a landmine is “a munition designed to be placed under, on or near the ground or other surface area and to be exploded by the presence, proximity or contact of a person or a vehicle”.

The convention, also informally known as the Ottawa Treaty after the location of its drafting and signing, bans the use of anti-personnel landmines, building on the 1980 Convention on Certain Conventional Weapons (CCW) Protocol II, which regulates the use of landmines and booby traps by states but does not comprehensively ban any specific type of mine.

Victim-activated improvised explosive devices (IEDs) are also outlawed, including IEDs activated by tripwires, pressure plates, or self-detonation, such as suicide or car bombs.

While the treaty has been widely successful at curbing the production and use of commercially made landmines by states (notable holdouts are Myanmar, North Korea, and Syria), non-state actors are increasingly using victim-activated improvised landmines.

The Landmine and Cluster Munition Monitor found evidence that non-state armed groups had used anti-personnel mines, including victim-activated improvised mines, in at least 10 countries in 2015: Afghanistan, Colombia, Iraq, Libya, Myanmar, Pakistan, Syria, Ukraine, and Yemen, as well as Nigeria – the most recent addition to the list.

The publication counted 6,461 deaths and injuries due to mines in the same year – a 75 percent increase from 2014 statistics and a 10-year high. Enduring armed conflicts in Afghanistan, Iraq, Libya, Syria, Ukraine, and Yemen are the main culprits for the spike in civilian casualties, but an increased availability of data likely plays a role too. Seventy-eight percent of landmine deaths were civilians, and 38 percent of civilian deaths were children.

In Yemen, HRW has documented numerous civilian deaths due to victim-activated landmines since the start of the conflict in 2015 – Houthi rebels have been using landmines as part of their fight against the Saudi Arabia-led coalition and its allies.

“Non-state actors [like IS and the Houthis] tend to be destructively creative and often don’t feel any compunction to be bound by international law,” Jeff Abramson, programme manager of TheMonitor and senior fellow at the Arms Control Association, explained.

In Syria and Iraq though, IS is using improvised mines on a scale that mimics “classical” state use (as deployed to deadly effect in the first two world wars), Hiznay told IRIN.

“We’re seeing large minefields intended to slow down or turn an enemy, and big minefields being put around a town to keep people in,” he said.

While the landmine portion of the Land Mine treaty is clear, legally it gets murkier when it comes to IEDs, especially when they are used by non-state actors.

Reports indicate that IS is leaving a complex array of booby traps littered across liberated urban areas. From Fallujah to Ramadi and now Mosul, Iraqi and coalition forces have uncovered thousands of buried explosives and tripwires. The same goes for former IS areas in Syria and Libya. In northern Syria, IEDs have been planted in streets, houses and even teddy bears, left to cause further harm to families as they return to liberated areas, according to a Médecins Sans Frontières report released this week.

“International law has difficulty with improvised things because they can take so many forms,” Maya Brehm, a researcher in weapons law at the Geneva Academy of International Humanitarian Law and Human Rights, told IRIN. “So it is a bit more difficult to create legislation that applies to [improvised weapons].”

It’s not that the international community hasn’t tried. In 2016, the UN General Assembly adopted a resolution on “countering the threat posed by improvised explosive devices”. The text encourages states to develop their own national policies to counter the use of IEDs and better protect stockpiles.

Brehm sees this as a step in the right direction: “A portion of the materials that non-state actors use for improvised devices are either stolen or diverted from national stocks, so if states were capable and willing to appropriately control their stock limits and control their stocks, and not to transfer weapons illegally to non-state actors, that is at least a partial solution to the problem.”

Brehm believes that if states publicly committed to a higher standard this would create greater general expectations that could then be used in talks with non-state armed groups like militias. She noted the work of organisations like Geneva Call, which attempts to get non-state actors on board with international humanitarian law.

It’s a daunting task, for reasons Brehm explained. “How can you ask non-state armed groups, who do not have access to officially manufactured weapons, to give up the use of IEDs, and at the same time you bomb them from the air? It is really not possible, politically.”